1. Field of the Invention
The present invention relates to miniature, unmanned aircraft and provides high altitude capabilities. More particularly, the present invention relates to a compact, light weight, low cost reciprocating piston engine having a supercharging arrangement suitable for enabling high altitude operation.
2. Description of the Prior Art
Unmanned aircraft, particularly those remotely controlled by radio frequency signals, are generally limited in altitude capabilities. High altitude operation is conducted under conditions of reduced air density and also of decreasing relative oxygen content of the air. Turbine engines are able to accommodate high altitude flight, but are impractical in certain roles. Reciprocating piston engines require supercharging to cope with high altitudes. Turbocharging can overcome oxygen deficiency at high altitude, but just as in the case of turbine engines, turbocharged engines are impractical in certain roles.
The role envisioned by the present invention concerns data acquisition and transmission of data from miniature, unmanned aircraft. An example of data acquisition is gathering of aerial imagery. Digital imagery or relayed messages provide examples of data transmission which may be performed by such aircraft. For maximum practicality and minimum costs, such aircraft must be free of licensing requirements imposed by the Federal Aviation Administration. This requires that the aircraft be less than fifty-five pounds in weight, restricted to maximum velocity capability of two hundred miles per hour, and constrained to obtain navigation or flight direction signals remotely.
Such aircraft can be built at reasonable costs using much technology available for so-called “model” aircraft. Apart from the above noted problem of oxygen deficiency, there is no reason why an aircraft powered by a reciprocating piston engine cannot fly at altitudes of twenty thousand feet and beyond. However, commercially available two- and four-stroke engines of one and two cylinders cannot cope with these high altitudes. It would be impractical to provide such engines with turbochargers and even with blower type superchargers due to constraints relating to bulk, weight, and costs. The use of turbine engines also presents problems unique to that type of engines. There remains a need for a compact, light weight, inexpensive apparatus for supercharging a reciprocating piston powered aircraft of less than fifty-five pounds gross weight.